Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;

int h,w,bl=0,wh=0,d=0;
int x[4]={1,-1,0,0};
int y[4]={0,0,1,-1};

char memo[51][51];
int memod[51][51]={0};
queue<pair<int,int>> qu;

int main(){
  int i,j,ans;
  pair<int,int> now,next;
  cin >> h >> w;
  for(i=1;i<=h;i++){
    for(j=1;j<=w;j++){
      cin >> memo[i][j];
      if(memo[i][j]=='.')wh++;
      else bl++;
    }
  }
  
  now = make_pair(1,1);
  qu.push(now);
  while(qu.size()){
    now = qu.front();
    qu.pop();
    for(i=0;i<4;i++){
      next = make_pair(now.first+x[i],now.second+y[i]);
      if(next.first>=1&&next.first<=h&&next.second>=1&&next.second<=w&&memo[next.first][next.second]=='.'){
	d++;
	memo[next.first][next.second]='#';
	qu.push(next);
	memod[next.first][next.second] = memod[now.first][now.second] +1;
      }
    }
  }
  ans = h*w-bl-memod[h][w]-1;
  if(memod[h][w]!=0)cout << ans << endl;
  else cout << -1 << endl;
  return 0;


    
  }